The invention relates to a condensation dryer, in particular a tumble dryer, comprising a heat exchanger for the condensation of moisture from an air circuit, which has been absorbed in a drying chamber and a method for operating a condensation dryer.
One differentiates on the one side traditional dryers, where the resulting hot humid air is usually vented outside, and on the other side condensation dryers. The invention relates to a condensation dryer, in which air is located in a closed air circuit within the dryer. In this closed air circulation, process air is heated in a first step. The dry warm process air passes through a drying chamber. The drying chamber is usually performed as a drum. The dry warm process air passes through the wet laundry and absorbs humidity.
The moisture-laden process air flows from the drying chamber into a heat exchanger for the condensation of moisture from the air circuit. This heat exchanger is usually located under the drum and is sometimes called a condenser. The heat exchanger has the task to condense the moisture from the closed “loop” of circulating air. Therefore the hot humid process air is cooled down.
In conventional condensation dryers a fan, which is coupled to the drum motor, promotes the movement of cool ambient fresh air through the heat exchanger. The cool fresh air, which is called “outside loop”, is separated from the closed air circulation of the process air, which is called “inside loop”, by heat-transferring walls. Heat exchangers of this category are also known as recuperators. The “inside loop” of air is sealed from the outside environment. The flow of cool “outside” fresh air is directed generally transversely to the flow of the “inside” process air. Such a flow arrangement is also known as cross-flow.
In the heat exchanger, the air is cooled below the dew point and moisture condenses from the process air. The fluid accumulates in a downstream bin. The condensed water is conveyed via a cyclically operating pump into a container, which is often mounted adjacent to the operating unit. The container has to be emptied regularly. After the deposition of the moisture the process air is reheated and recycled to the drying chamber.
DE 695 25 350 T2 discloses a condensation dryer, which comprises a zeolite adsorption system. The system consists of an adsorber-desorber, which contains zeolite as a solid adsorbent and an evaporator-condenser, which contains water. This zeolite adsorption system is located after a heat exchanger, which condenses from an air circuit. The condensation efficiency of the heat exchanger is not improved in this condensation dryer.
DE 103 56 786 A1 discloses a process for drying in a domestic appliance. The household appliance comprises a container with water and a sorber with reversibly dehydratable material such as zeolite. In the sorber an electrical heating element is present, which can heat the reversibly dehydratable material for desorption. The sorber and the container are connected via a pipe. Both the container and the sorber are positioned in a closed air circuit of the domestic appliance. In difference to the invention this household appliance does not have a heat exchanger for the condensation of moisture from the process air flow.